1. Field of the Invention
The present invention generally relates to the storage of exothermic materials and, in particular, to systems and methods for storing exothermic materials that are adapted to maintain the stored materials at suitable temperatures.
2. Description of the Related Art
Exothermic materials inherently suffer from problems associated with their storage. For instance, nuclear fuel discharged from fission reactors, referred to hereinafter as Spent Nuclear Fuel (SNF), typically is stored in deep pools filled with water, with the water being provided to dissipate heat and to attenuate gamma and neutron radiation generated by the SNF. As an alternative to storing SNF in water-filled pools (xe2x80x9cwet storagexe2x80x9d), xe2x80x9cdry storagexe2x80x9d techniques also have been utilized.
In a typical dry-storage application, the SNF is stored in a substantially horizontal or substantially vertical configuration within a protective vessel which, typically, includes a heavy-walled structure referred to as a xe2x80x9ccaskxe2x80x9d or xe2x80x9coverpack.xe2x80x9d The aforementioned overpack provides, among other functions, radiation shielding and heat removal for the SNF. The overpack, therefore, typically is formed of heat resistant and shielding efficient material so that it can perform shielding and heat removal for extended time periods. However, since more and more SNF is envisioned as having high residual decay heat due to more extensive fissioning in the fuel during its operation in reactor, as well as shorter cooling times in deep water-filled pools, many prior art storage systems are not well suited for long-term storage of these materials.
Therefore, there is a need for improved systems and methods which address these and other shortcomings of the prior art.
Briefly described, the present invention relates to the storage of exothermic materials and, in particular, to systems and methods for storing exothermic materials that are adapted to maintain the stored materials at suitable temperatures. In a preferred embodiment, a system for storing exothermic materials is provided which includes a first canister and a second canister. Preferably, the first canister incorporates a canister wall defining a first storage volume that is adapted to receive exothermic material therein. The second canister incorporates an inner wall and an outer wall, with the inner wall defining a canister-receiving volume that is adapted to receive at least a portion of the first canister therein. Additionally, the outer wall and the inner wall may define a second storage volume which is adapted to receive exothermic material therein.
In another embodiment, a system for storing exothermic materials includes first means for storing exothermic material therein and second means for receiving at least a portion of the first means therein. Preferably, the second means also is adapted to receive exothermic material therein.
The present invention also may be construed as providing methods for storing exothermic materials. A preferred method includes the steps of: providing a first canister having a canister wall defining a first storage volume, the first storage volume being adapted to receive exothermic material therein; providing a second canister having an inner wall and an outer wall, the inner wall defining a canister-receiving volume adapted to receive at least a portion of the first canister therein, the outer wall and the inner wall defining a second storage volume therebetween; and inserting at least a portion of the first canister within the canister-receiving volume.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such features and advantages be included herein within the scope of the present invention, as defined in the appended claims.